In a related art idle controlling device of an engine, to activate a catalyst at an early stage when the engine is cold, an ignition timing is controlled to be retarded, and an intake air quantity is controlled, so that feedback control is performed for setting the rotational speed of the engine to a target idle rotational speed.
However, the above-described related art idle controlling device of the engine controls engine torque so that the rotational speed of the engine becomes the target idle rotational speed while correcting the ignition timing and the intake air quantity at the same time. For providing torque, when the ignition timing is advanced, an exhaust temperature is reduced, whereas, when the intake air quantity is increased, the exhaust temperature is increased. Therefore, when the ignition timing and the intake air quantity are corrected at the same time, it is difficult to adjust to a suitable exhaust temperature when the engine is cold.